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Another boat, carrying 40 people, has been intercepted west of Christmas Island by HMAS Bathurst.

Speaking to Dateline, former G4S senior manager Rod St George said some Manus Island inmates were left locked up with men who had already raped them, and others were bashed and forced to sew their lips together in a protest about conditions at the centre.

He also confirmed an instance where a man was left with a perforated eardrum after solvent was poured in his ear.

Burke says he knew of the claims earlier this month

Speaking on Radio National, Mr Burke said he was made aware of the allegations a week and a half ago, but only spoke to Mr St George for the first time last night.

"The allegations were horrific. I wish I'd had an opportunity to get the specifics of them earlier than last night because I would've started acting on them earlier than last night," Mr Burke said.

"You want to make sure that people are being treated with dignity. You want to make sure that services are being provided appropriately.

"The allegations on the program last night clearly fell appallingly short of that, and clearly there's a lot of direct allegations that need to be followed up."

Inmates 'lived in constant fear of rapes, bashings'

Mr St George, who no longer works on the island, said "vulnerable" inmates live in constant fear of attack.

"There was nothing that could be done for these young men who were considered vulnerable, which in many cases is just a euphemism for men who have been raped," he said.

"They couldn't go to the toilet unassisted, they couldn't shower. Some of them were even changing tents constantly so they couldn't be tracked down."

He said the PNG nationals employed as security guards on Manus Island were not up to the task.

"If there was something going to happen, an attack for instance, they might be told by the perpetrators 'walk away', and they would comply," he said.